DNA image cytometry of keratoacanthoma and squamous cell carcinoma

IMP-3 expression in keratoacanthomas and squamous cell carcinomas of the skin: an immunohistochemical study

The protein insulin-like growth factor II mRNA binding protein 3 (IMP-3) is an important factor for cell migration and adhesion in malignancies. Recent studies have shown a remarkable overexpression of IMP-3 in different human malignant neoplasms and also revealed it as an important prognostic marker in some tumor entities. The purpose of this study is to compare IMP-3 immunostaining in cutaneous squamous cell tumors and determine whether IMP-3 can aid in the differential diagnosis of these lesions. To our knowledge, IMP-3 expression has not been investigated in skin squamous cell proliferations thus far. Immunohi-stochemical staining for IMP-3 was performed on slides organized by samples from 67 patients, 34 with keratoacanthoma (KA) and 33 with primary cutaneous squamous cell carcinoma (SCC) (16 invasive and 17 in situ). Seventyfour percent of KAs (25/34) were negative for IMP-3 staining, while 57% of SCCs (19/33) were positive for IMP-3 staining. The percentage of IMP-3 positive cells increased significantly in the invasive SCC group (P=0.0111), and particularly in the SCC in situ group (P=0.0021) with respect to the KA group. IMP-3 intensity staining was significantly higher in invasive SCCs (P=0.0213), and particularly in SCCs in situ (P=0.008) with respect to KA. Our data show that IMP-3 expression is different in keratoacanthoma with respect to squamous cell carcinoma. IMP-3 assessment and staining pattern, together with a careful histological study, can be useful in the differential diagnosis between KA e SCC.

Keratoacanthoma: facts and controversies

The keratoacanthoma and its variants are clinically and histologically heterogenous. Some consider the keratoacanthoma to be benign, whereas others classify it as a subtype of squamous cell carcinoma. The keratoacanthoma is generally treated rather than observed for spontaneous resolution. This hampers evaluation of the true natural history of lesions diagnosed as keratoacanthoma. In addition, studies have not found a reliable marker to differentiate keratoacanthoma from squamous cell carcinoma. It currently remains unclear how the keratoacanthoma relates to squamous cell carcinoma, and continued investigation is necessary.

Cytogenetic alterations in nonmelanoma skin cancer: a review

Since the advent of cytogenetic analysis, knowledge about fundamental aspects of cancer biology has increased, allowing the processes of cancer development and progression to be more fully understood and appreciated. Classical cytogenetic analysis of solid tumors had been considered difficult, but new advances in culturing techniques and the addition of new cytogenetic technologies have enabled a more comprehensive analysis of chromosomal aberrations associated with solid tumors. Our purpose in this review is to discuss the cytogenetic findings on a number of nonmelanoma skin cancers, including squamous- and basal cell carcinomas, keratoacanthoma, squamous cell carcinoma in situ (Bowen's disease), and solar keratosis. Through classical cytogenetic techniques, as well as fluorescence-based techniques such as fluorescence in situ hybridization and comparative genomic hybridization, numerous chromosomal alterations have been identified. These aberrations may aid in further defining the stages and classifications of nonmelanoma skin cancer and also may implicate chromosomal regions involved in progression and metastatic potential. This information, along with the development of newer technologies (including laser capture microdissection and comparative genomic hybridization arrays) that allow for more refined analysis, will continue to increase our knowledge about the role of chromosomal events at all stages of cancer development and progression and, more specifically, about how they are associated with nonmelanoma skin cancer.

Comparative study of fibrous dysplasia and osteofibrous dysplasia: histopathological, immunohistochemical, argyrophilic nucleolar organizer region and DNA ploidy analysis

Fibrous dysplasia and osteofibrous dysplasia are both benign fibro-osseous lesions of the bone. We retrospectively studied the clinicopathological findings in 90 cases of fibrous dysplasia and 17 cases of osteofibrous dysplasia. In these cases, the expression of proliferating cell nuclear antigen (PCNA) and the presence of argyrophilic nucleolar organizer regions (AgNOR), as well as DNA ploidy, were examined. The bones affected by fibrous dysplasia were the maxilla, femur and frontal bone. Osteofibrous dysplasia occurred exclusively in the tibia or fibula. The average age of patients with fibrous dysplasia (24.0 years) was higher than that of patients with osteofibrous dysplasia (12.9 years). Fibrous dysplasias were divided into four major histological subtypes: Pagetoid, Chinese alphabet, small bone and parallel bone. Bone lining cells, which are known as resting osteoblasts, were seen in some cases of fibrous dysplasia. Cartilage differentiation was not seen in osteofibrous dysplasia. PCNA expression was strongly positive in the nuclei of osteoblasts around the bone trabeculae in osteofibrous dysplasia, but negative in the nuclei of bone lining cells around the bone trabeculae in fibrous dysplasia. The number of AgNOR in osteofibrous dysplasia was slightly higher than that in fibrous dysplasia. Both fibrous dysplasia and osteofibrous dysplasia were diploid. These features suggest that fibrous dysplasia can be differentiated from osteofibrous dysplasia by anatomical site, patient age, histological appearance, cartilage differentiation and PCNA positivity. DNA content by image cytometry is not a useful tool for differentiating these two diseases.

DNA image cytometry on sections as compared with image cytometry on smears and flow cytometry in melanoma

DNA measurements of 130 melanomas were carried out by flow cytometry (FCM) and image cytometry (ICM). ICM was applied to cytological preparations of fresh material (cICM) and to sections of formalin-fixed paraffin embedded tissue (sICM). The DNA ploidy, the DNA index of G0/G1 peaks (DI), and the proliferation index (PI) were used to compare all the methods. The following parameters reflecting malignancy were calculated only from ICM histograms: the 5c exceeding rate (5cER) and the malignancy grade (MG). In cases found to be DNA aneuploid by FCM, the PI values (FCM versus cICM) and the DIs (between all methods) showed a high correlation, and the concordance in relation to the DNA ploidy status was 96% (FCM versus cICM) and 94% (FCM versus sICM). However, we ascertained essential differences between FCM and ICM in melanomas classified as DNA diploid by FCM. The concordance in DNA ploidy was only 66% (FCM versus cICM) and 64% (FCM versus sICM). In contrast, cICM and sICM yielded similar results in most cases. With the exception of the near diploid range, ICM is superior to FCM in detecting DNA aneuploidy. In particular, DNA tetraploid stem lines can easily be overlooked by FCM. Therefore, DNA measurements of tumours judged to be DNA diploid by FCM must be verified by ICM. ICM on sections proved to be applicable and yielded reliable results provided that a suitable thickness was used, and the measuring of sectioned and overlapping nuclei was largely avoided by careful focusing in either direction.

Loss of heterozygosity analysis of keratoacanthoma reveals multiple differences from cutaneous squamous cell carcinoma

Keratoacanthomas (KAs) resemble squamous cell carcinomas (SCCs) except that, unlike SCCs, after a period of rapid growth over a few months they involute completely. The basis of their regressing natural history is not known. We have examined keratoacanthomas and another benign cutaneous tumour, the basal cell papilloma (BCP), for loss of heterozygosity (LOH) at a number of loci that are frequently lost in SCCs and other skin tumours. The frequency of LOH for both KAs and BCPs was low, with only isolated losses identified at 9p, 9q and 10q in KAs [fractional allelic loss (FAL) was 1.3%], and at 9p and 17p in BCPs (FAL was 0.4%). This contrasts with previous work showing a FAL of 32% in SCC and 46% in actinic keratoses. The results show a clear difference between KA and SCC and do not support the hypothesis that KAs are SCCs that regress as a result of external (host) influences but rather suggest that KAs and SCCs are different de novo. LOH around the locus implicated in the multiple self-healing epitheliomata of Ferguson-Smith (9q22-q31) was shown in only 1 of 11 KAs.

DNA ploidy in nonmelanoma skin cancer

BACKGROUND

Patients with head and neck squamous cell carcinoma die of locoregional recurrence and those with basal cell carcinoma suffer cosmetic and functional changes from its treatment. Prognostic factors are based upon tumor characteristics and host factors. Flow cytometry can assist with prognostic characterization of nonmelanoma skin cancer.

METHODS

Specimens from 40 sequential patients with head and neck nonmelanoma skin cancers were prospectively obtained at the time of surgery. The patients were followed for four years for local recurrence and metastasis to regional lymph nodes. Samples were prepared from frozen specimens using a modification of the Vindelov procedure.

RESULTS

DNA aneuploidy or tetraploidy and histology of well differentiated squamous cell carcinoma were significantly associated with metastasis to regional lymph nodes. Direct extension of tumor below the adipose tissue was associated with an S-phase greater than 4.1 and a proliferative fraction greater than 5.5. No tumors recurred at the site of surgical resection.

CONCLUSIONS

The measurement of DNA ploidy of well differentiated squamous cell carcinoma, and proliferative capacity or S-phase of both basal cell and squamous cell carcinomas assists in predicting the biologic proclivity for locoregional invasion or metastasis of nonmelanoma skin cancer. Identification of aggressive tumors at the time of surgery may offer the opportunity for prevention of lethal metastasis by using adjunctive therapy.

Image analysis in dermatopathology

BACKGROUND/AIMS

Image analysis in dermatopathology has been used for DNA ploidy analysis, morphometry, stereology, and quantitative immunohistochemistry. The object is to review image analysis in dermatopathology and evaluate these modalities and their application in pigmented lesion pathology, for elucidation of tumor behaviour and architecture and as an aid in tumor identification and prognostication.

CONCLUSION

Image analysis in dermapathology has a huge potential. The techniques are difficult and at present mainly used in specialized centres.

Spontaneous regression of human melanoma/nonmelanoma skin cancer: association with infiltrating CD4+ T cells

Spontaneous regression occurs in some human malignant melanomas and basal cell carcinomas (BCCs). We have compared the cellular infiltrate in regressing and nonregressing tumors in order to analyze the mechanism by which regression occurs. Regressing primary melanomas and BCCs were infiltrated with a larger number of CD4+, but not CD8+, T lymphocytes than were seen in nonregressing tumors. The number of interleukin 2 receptor-positive (early activation marker) but not transferrin receptor-positive (intermediate activation marker) T cells was increased, indicating that the infiltrating T cells were activated. Large numbers of Langerhans cells, macrophages, and other class II major histocompatibility complex (MHC)-expressing cells were present but were not increased in the regressing tumors. There were no detectable B lymphocytes, and the regressing tumor cells displayed levels of HLA-DR expression similar to those of the nonregressing tumors. Comparison of squamous cell carcinoma (SCCs) with keratoacanthomas (KAs), which are likely to be a spontaneously regressing form of SCC, also showed increased infiltration of activated CD4+, but not CD8+, T cells within the KA. A murine ultraviolet (UV)-induced squamous tumor that spontaneously regresses when transplanted into immunocompetent syngeneic mice was also infiltrated with increased numbers of activated CD4+, but not CD8+, T cells prior to and during rejection. These results indicate that spontaneous regression of human skin tumors is likely to be immunologically mediated, and that CD4+ T lymphocytes seem to mediate this regression.

Keratoacanthoma: a deficient squamous cell carcinoma? Study of bcl-2 expression

Ten keratoacanthomas with both proliferative and regressive histologic features along with 10 well-differentiated squamous cell carcinomas were examined using immunohistochemistry for the expression of bcl-2, a protooncogene recently recognized to be involved in protecting cells from undergoing apoptosis. The squamous cell carcinomas had a modest but diffuse staining pattern, while the proliferative keratoacanthomas stained only at the basal cells and only rare cells stained positively in the regressive keratoacanthomas. The degree and pattern of staining suggest a loss of bcl-2 expression with tumor maturity in keratoacanthoma and a possible role in their ultimate involution.

Evidence that regression in keratoacanthoma is immunologically mediated: a comparison with squamous cell carcinoma

Recent research observations suggest that the keratoacanthoma (KA) is a form of resolving squamous cell carcinoma (SCC). The mechanism by which this resolution takes place has not been fully explored, although it may have an immunological basis. To investigate this, we compared 15 clinically and histologically diagnosed KAs and 15 SCCs with regard to cellular infiltrate and keratin expression. We found that KAs have significantly higher numbers of CD3+ and CD4+ cells invading their epidermal component than SCCs. The T lymphocytes infiltrating KAs were more immunologically active, as greater numbers expressed the interleukin-2 receptor (IL-2R) than those in SCCs. It is of interest that CD36 was expressed by a significantly greater proportion of tumour cells within KAs than SCCs. This was also the case for the intercellular adhesion molecule ICAM-1, and the differentiation marker keratin 10. Overall, these findings suggest that KA regression is immunologically mediated, with activated (IL-2R+) CD4+ T lymphocytes and adhesion molecules playing a pivotal role in the immune response.

Keratoacanthoma

The keratoacanthoma is a common cutaneous neoplasm that most often occurs on sun-exposed sites in light-skinned persons of middle age or older. It is considered the prototype of cutaneous pseudo-malignancies because it is a rapidly growing tumor with a histologic pattern resembling squamous cell carcinoma. It may be best viewed as an aborted malignancy that only rarely progresses into an invasive squamous cell carcinoma. It is most likely derived from hair follicle cells. The common type of keratoacanthoma and its many variants are discussed with emphasis on clinical and histologic features, biologic behavior, and response to therapy.